Question

Arrange the following compounds in the increasing order of their reactivity towards HCN. (i) Acetaldehyde (ii) Acetone (iii) Di ? tert ? butyl ketone (iv) Methyl ?tert ?butyl ketone

• A. $ ~\text{III }<\text{ II }<\text{ IV }<\text{ I} $
• B. $ \text{II }<\text{ I }<\text{ IV }<\text{ II} $
• C. $ ~\text{IV }<\text{ III }<\text{ II }<\text{ I} $
• D. $ ~\text{II }<\text{ IV }<\text{ I }<\text{ III} $

Answer 1

Answer: (D)

More electron withdrawing group favours NA reaction (nucleophilic addition reaction), whereas electron donating group decreases reactivity towards NA reaction or reactivity towards HCN. Decreasing order of NA reactivity.
So, increasing order of reactivity towards HCN $ \text{IV III II I} $